Prof David Stuart FRS
| Research Area: | Protein Science and Structural Biology |
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| Technology Exchange: | Bioinformatics, Computational biology, Crystallography and Protein interaction |
| Keywords: | Viral Proteins, X Ray crystallographic methods, Viruses, virus-receptor interactions, retroviruses and structure to function of genome |
| Web Links: |
Viruses are attractive targets for study at the molecular level, since they are sufficiently simple that we may hope to achieve a rather complete understanding of their biology. In practice although their genomes are compact they display astonishing diversity, both in structure and function. Our attempts to relate structure to function have benefited from the developments in X-ray crystallographic methods that have brought very complex structures within reach of description in atomic detail. Our targets range from picornaviruses, small ssRNA viruses, which include a number of important animal and human pathogens, to the larger dsRNA viruses. At both ends of this spectrum (from less than 10,000,000 to about 100,000,000 Daltons) we now have representative atomic structures.
Our efforts are particularly focused on virus-receptor interactions and basic puzzles of virus assembly. Our studies here are highly collaborative, with strong links with a number of virologists (P. Mertens and B. Charleston (Pirbright), D. Rowlands (Leeds), P. Roy (London) as well as numerous groups elsewhere in Europe).
Work on cell-surface molecules is largely performed in collaboration with the group of Prof. E.Y. Jones, whose entry describes many of the projects.
We have a particular interest in studying virus evolution and many of these studies are perfoirmed in collaboration with D. Bamford in Helsinki.
Finally, we are studying a number of viral proteins and enzymes which are potential drug targets and/or illuminate how viruses modulate host responses. For example, the immune modulators of pox viruses.
| Name | Department | Institution | Country |
|---|---|---|---|
| Dennis Bamford | University of Helsinki | Finland |
2009. Equine rhinitis A virus and its low pH empty particle: clues towards an aphthovirus entry mechanism? PLoS Pathog, 5 (10), pp. e1000620. Read abstract | Read more
Equine rhinitis A virus (ERAV) is closely related to foot-and-mouth disease virus (FMDV), belonging to the genus Aphthovirus of the Picornaviridae. How picornaviruses introduce their RNA genome into the cytoplasm of the host cell to initiate replication is unclear since they have no lipid envelope to facilitate fusion with cellular membranes. It has been thought that the dissociation of the FMDV particle into pentameric subunits at acidic pH is the mechanism for genome release during cell entry, but this raises the problem of how transfer across the endosome membrane of the genome might be facilitated. In contrast, most other picornaviruses form 'altered' particle intermediates (not reported for aphthoviruses) thought to induce membrane pores through which the genome can be transferred. Here we show that ERAV, like FMDV, dissociates into pentamers at mildly acidic pH but demonstrate that dissociation is preceded by the transient formation of empty 80S particles which have released their genome and may represent novel biologically relevant intermediates in the aphthovirus cell entry process. The crystal structures of the native ERAV virus and a low pH form have been determined via highly efficient crystallization and data collection strategies, required due to low virus yields. ERAV is closely similar to FMDV for VP2, VP3 and part of VP4 but VP1 diverges, to give a particle with a pitted surface, as seen in cardioviruses. The low pH particle has internal structure consistent with it representing a pre-dissociation cell entry intermediate. These results suggest a unified mechanism of picornavirus cell entry. Hide abstract
2008. The postfusion structure of baculovirus gp64 supports a unified view of viral fusion machines. Nat Struct Mol Biol, 15 (10), pp. 1024-1030. Read abstract | Read more
Viral fusion proteins mediate the merger of host and viral membranes during cell entry for all enveloped viruses. Baculovirus glycoprotein gp64 (gp64) is unusual in promoting entry into both insect and mammalian cells and is distinct from established class I and class II fusion proteins. We report the crystal structure of its postfusion form, which explains a number of gp64's biological properties including its cellular promiscuity, identifies the fusion peptides and shows it to be the third representative of a new class (III) of fusion proteins with unexpected structural homology with vesicular stomatitis virus G and herpes simplex virus type 1 gB proteins. We show that domains of class III proteins have counterparts in both class I and II proteins, suggesting that all these viral fusion machines are structurally more related than previously thought. Hide abstract
2008. Insights into virus evolution and membrane biogenesis from the structure of the marine lipid-containing bacteriophage PM2. Mol Cell, 31 (5), pp. 749-761. Read abstract | Read more
Recent, primarily structural observations indicate that related viruses, harboring no sequence similarity, infect hosts of different domains of life. One such clade of viruses, defined by common capsid architecture and coat protein fold, is the so-called PRD1-adenovirus lineage. Here we report the structure of the marine lipid-containing bacteriophage PM2 determined by crystallographic analyses of the entire approximately 45 MDa virion and of the outer coat proteins P1 and P2, revealing PM2 to be a primeval member of the PRD1-adenovirus lineage with an icosahedral shell and canonical double beta barrel major coat protein. The view of the lipid bilayer, richly decorated with membrane proteins, constitutes a rare visualization of an in vivo membrane. The viral membrane proteins P3 and P6 are organized into a lattice, suggesting a possible assembly pathway to produce the mature virus. Hide abstract
2008. Paired receptor specificity explained by structures of signal regulatory proteins alone and complexed with CD47. Mol Cell, 31 (2), pp. 266-277. Read abstract | Read more
CD47 is a widely distributed cell-surface protein that acts a marker of self through interactions of myeloid and neural cells. We describe the high-resolution X-ray crystallographic structures of the immunoglobulin superfamily domain of CD47 alone and in complex with the N-terminal ligand-binding domain of signal regulatory protein alpha (SIRPalpha). The unusual and convoluted interacting face of CD47, comprising the N terminus and loops at the end of the domain, intercalates with the corresponding regions in SIRPalpha. We have also determined structures of the N-terminal domains of SIRPbeta, SIRPbeta(2), and SIRPgamma; proteins that are closely related to SIRPalpha but bind CD47 with negligible or reduced affinity. These results explain the specificity of CD47 for the SIRP family of paired receptors in atomic detail. Analysis of SIRPalpha polymorphisms suggests that these, as well as the activating SIRPs, may have evolved to counteract pathogen binding to the inhibitory SIRPalpha receptor. Hide abstract
2008. Structural basis of Nipah and Hendra virus attachment to their cell-surface receptor ephrin-B2. Nat Struct Mol Biol, 15 (6), pp. 567-572. Read abstract | Read more
Nipah and Hendra viruses are emergent paramyxoviruses, causing disease characterized by rapid onset and high mortality rates, resulting in their classification as Biosafety Level 4 pathogens. Their attachment glycoproteins are essential for the recognition of the cell-surface receptors ephrin-B2 (EFNB2) and ephrin-B3 (EFNB3). Here we report crystal structures of both Nipah and Hendra attachment glycoproteins in complex with human EFNB2. In contrast to previously solved paramyxovirus attachment complexes, which are mediated by sialic acid interactions, the Nipah and Hendra complexes are maintained by an extensive protein-protein interface, including a crucial phenylalanine side chain on EFNB2 that fits snugly into a hydrophobic pocket on the viral protein. By analogy with the development of antivirals against sialic acid binding viruses, these results provide a structural template to target antiviral inhibition of protein-protein interactions. Hide abstract
2004. Insights into assembly from structural analysis of bacteriophage PRD1. Nature, 432 (7013), pp. 68-74. Read abstract | Read more
The structure of the membrane-containing bacteriophage PRD1 has been determined by X-ray crystallography at about 4 A resolution. Here we describe the structure and location of proteins P3, P16, P30 and P31. Different structural proteins seem to have specialist roles in controlling virus assembly. The linearly extended P30 appears to nucleate the formation of the icosahedral facets (composed of trimers of the major capsid protein, P3) and acts as a molecular tape-measure, defining the size of the virus and cementing the facets together. Pentamers of P31 form the vertex base, interlocking with subunits of P3 and interacting with the membrane protein P16. The architectural similarities with adenovirus and one of the largest known virus particles PBCV-1 support the notion that the mechanism of assembly of PRD1 is scaleable and applies across the major viral lineage formed by these viruses. Hide abstract
2004. Membrane structure and interactions with protein and DNA in bacteriophage PRD1. Nature, 432 (7013), pp. 122-125. Read abstract | Read more
Membranes are essential for selectively controlling the passage of molecules in and out of cells and mediating the response of cells to their environment. Biological membranes and their associated proteins present considerable difficulties for structural analysis. Although enveloped viruses have been imaged at about 9 A resolution by cryo-electron microscopy and image reconstruction, no detailed crystallographic structure of a membrane system has been described. The structure of the bacteriophage PRD1 particle, determined by X-ray crystallography at about 4 A resolution, allows the first detailed analysis of a membrane-containing virus. The architecture of the viral capsid and its implications for virus assembly are presented in the accompanying paper. Here we show that the electron density also reveals the icosahedral lipid bilayer, beneath the protein capsid, enveloping the viral DNA. The viral membrane contains about 26,000 lipid molecules asymmetrically distributed between the membrane leaflets. The inner leaflet is composed predominantly of zwitterionic phosphatidylethanolamine molecules, facilitating a very close interaction with the viral DNA, which we estimate to be packaged to a pressure of about 45 atm, factors that are likely to be important during membrane-mediated DNA translocation into the host cell. In contrast, the outer leaflet is enriched in phosphatidylglycerol and cardiolipin, which show a marked lateral segregation within the icosahedral asymmetric unit. In addition, the lipid headgroups show a surprising degree of order. Hide abstract
2004. Atomic snapshots of an RNA packaging motor reveal conformational changes linking ATP hydrolysis to RNA translocation. Cell, 118 (6), pp. 743-755. Read abstract | Read more
Many viruses package their genome into preformed capsids using packaging motors powered by the hydrolysis of ATP. The hexameric ATPase P4 of dsRNA bacteriophage phi12, located at the vertices of the icosahedral capsid, is such a packaging motor. We have captured crystallographic structures of P4 for all the key points along the catalytic pathway, including apo, substrate analog bound, and product bound. Substrate and product binding have been observed as both binary complexes and ternary complexes with divalent cations. These structures reveal large movements of the putative RNA binding loop, which are coupled with nucleotide binding and hydrolysis, indicating how ATP hydrolysis drives RNA translocation through cooperative conformational changes. Two distinct conformations of bound nucleotide triphosphate suggest how hydrolysis is activated by RNA binding. This provides a model for chemomechanical coupling for a prototype of the large family of hexameric helicases and oligonucleotide translocating enzymes. Hide abstract
Structure-based strategies for better picornavirus vaccines
Project Overview Picornaviruses are responsible for a variety of human and animal diseases, ranging from hepatitis A, through polio to foot-and-mouth disease and the common cold. We have a track record in the structural analysis of several of these viruses and are now working closely with a number of groups to investigate if it is possible to design a generic approach to the development of improved vaccines by structure led redesign of the virus capsid. Our first target has been foot-and-mouth ...
Structure of the vaccinia virus host-cell fusion machine
Vaccinia virus is a large double-stranded DNA virus closely related to variola virus, the causative agent of smallpox. Although a concerted campaign of vaccination successfully eradicated smallpox over 20 years ago, the re-emergence of smallpox in society by its deliberate release and/or the emergence of monkeypox virus that can also infect humans pose a serious threat to human health. While it is known that poxviruses enter the host cell by the action of a large, multi-protein membrane-fusion ...
